Testing for Allergy - NCC Pediatrics Residency at Walter Reed

year when the child is symptomatic.
For example, trees usually pollinate
in early spring, grasses in late spring
to summer, and weeds from summer
through fall. The regional flora
determines pollen exposure. Most
flora causing significant allergic
reactions are wind-pollinated, and
their pollen can travel many miles.
For children who have perennial
symptoms, the likely allergens
include dust mites, pet dander, cockroach
spores, and mold spores.
Aeroallergen testing generally is
viewed as correlating well with the
patient’s symptoms. On the other
hand, food testing, whether by skin
tests or in vitro techniques, is
deemed less reliable. Caution should
be used when interpreting food skin
tests because only a small fraction
of patients who have a positive food
skin test will react when a doubleblind
placebo-controlled food challenge
is performed. The avoidance
of foods in the diet never should be
based on skin test or in vitro test
results alone. For children who have
a clinical allergic history of food
reactions, skin testing can help confirm
the suspected food allergen. It
also can be helpful in children who
have eczema, whose rash may be
triggered by ingestion of certain
foods. The most common food allergies
in children are to milk, wheat,
soy, egg, peanut, tree nuts, and fish.
Although many children outgrow
milk, wheat, soy, and egg allergy,
peanuts, tree nuts, and fish typically
elicit life-long reactions and can
result in severe, life-threatening anaphylaxis.
The practice of placing
children who supposedly have
extensive food allergies on highly
restrictive diets should be discouraged,
especially when the clinical
history does not reveal an allergic
response to the food ingestion. It is
important to remember that behavioral
issues such as poor sleeping,
crying, and hyperactivity, are
nonIgE reactions. A board-certified
allergist often can help families differentiate
between allergic (IgE)
reactions and food intolerances
(nonIgE).
Who is an Allergist?
The board-certified allergist has
completed a 2- to 3-year period of
concentrated study in the field of
allergic and immunologic diseases
after having completing a pediatric
or internal medicine residency.
Board certification entails successful
completion of the pediatric or internal
medicine boards and the allergy
and immunology boards. Like the
pediatric board certification, which
must be renewed every 7 years, the
allergy and immunology board certification
must be renewed every
10 years. In making a referral to a
board-certified/board-eligible allergist,
the primary care physician
should assume that an appropriate
history and physical examination
will be performed to determine
which diagnostic tests, including
skin tests, are indicated. Most
importantly, these tests will be interpreted
for the patient and the referring
physician. In addition, advice
for allergen avoidance and proper
medical management should be
discussed.
Conclusion
Allergy skin testing represents one
of the major tools in the diagnosis
of IgE-mediated diseases. When performed
properly, it yields important
information, but the interpretation of
these tests requires correlation with
the patient’s history and physical
examination because the presence of
IgE antibodies alone does not equate
with disease. Conferring with a
board-certified allergist should maximize
the care of the affected patient.
SUGGESTED READING
Bernstein IL, Storms WW. Practice parameters
for allergy diagnostic testing. Ann
Allergy Asthma Immunol. 1995;75(SIII):
543–625
Demoly P, Michel F-B, Bousquet J. In vivo
methods for study of allergy skin tests,
techniques, and interpretation. In: Middleton
E Jr, Reed CE, Ellis EF, et al, eds.
Allergy Principles and Practice. 5th ed. St.
Louis, Mo: Mosby-Year Book; 1998:
430–439
Ownby DR. Test for IgE antibody. In: Bierman
CW, Pearlman DS, Shapiro GG, et al,
eds. Allergy, Asthma, and Immunology
from Infancy to Adulthood. 3rd ed. Philadelphia,
Penn: WB Saunders Co; 1996:
144–156
Sly RM. Allergic disorders. In: Behrman RE,
Kliegman RM, Arvin AM, eds. Nelson
Textbook of Pediatrics. 15th ed. Philadelphia,
Penn: WB Saunders Co; 1996:
610–618
ALLERGY
Allergy Testing
PIR QUIZ
Quiz also available online at
www.pedsinreview.org.
1. You are asked to evaluate a
6-year-old child who has a known
history of asthma for allergy to
trees, grasses, and weeds. He is
being treated with inhaled
beclomethasone, albuterol,
cromolyn sodium, and theophylline
for reactive airway disease and
diphenhydramine for allergic
rhinitis. Which of the following is
most likely to interfere with allergy
skin testing?
A. Albuterol.
B. Beclomethasone
C. Cromolyn sodium.
D. Diphenhydramine.
E. Theophylline.
2. Which of the following allergenspecific
immunoglobulins is
involved in skin testing for allergy?
A. Immunoglobulin A.
B. Immunoglobulin D.
C. Immunoglobulin E.
D. Immunoglobulin G.
E. Immunoglobulin M.
3. You are evaluating a 12-year-old
girl who has atopic dermatitis and
allergy to multiple agents. Which
of the following is the most important
advantage of radioallergosorbent
test (RAST) over skin testing
for allergy?
A. Increased specificity in atopic
patients.
B. Lower cost.
C. Not influenced by antihistamines.
D. Rapidity of diagnosis.
E. Testing for greater number of
allergens.
4. Which of the following is a true
statement regarding testing for
allergy?
A. Avoidance of suspected food
allergen should be based on
skin testing.
B. Intradermal skin testing carries
lower risk of anaphylaxis
compared with percutaneous
skin testing.
C. Percutaneous skin testing has
high specificity but low sensitivity
for clinically significant
allergies.
D. RAST is more reliable than
skin testing.
E. Skin test reactivity is increased
in young infants.
Pediatrics in Review Vol. 21 No. 2 February 2000 43
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